Flipping the Switch on Electric School Buses: Cost Factors: Module 3 (Text Version)
This is a text version of the video for Flipping the Switch on Electric School Buses: Cost Factors: Module 3.
Welcome to the Flipping the Switch on Electric School Buses series, where we will discuss electric school bus cost factors. Flipping the Switch series, Electric School Bus Cost Factors consists of five modules. Module 1 provided information on bus capital costs and infrastructure costs. Module 2 discussed electric school bus operational costs. Module 3, which we are reviewing today, will discuss electric school bus maintenance costs. Module 4 will review electric bus incentives and financing options, and finally Module 5 will provide information on how to have some of those financing discussions.
So let's get started with Module 3 of the Electric School Bus Factors, Maintenance Costs. All right. So with all technologies it is important to track the maintenance cost to fully understand your total cost of ownership. With battery electric buses there are some comparative benefits to that of diesel systems that are expected to reduce some of the maintenance costs. One of the all time favorites so far has been no longer needing an after treatment system. So this means no diesel exhaust fluid and no diesel particulate filter, which has in the past been known to cause additional maintenance cost, timing, and parts and labor.
There is also no engine oil, and there are overall fewer mechanical components. So an EV motor contains about 20 moving components, where an internal combustion engine generally has more than 2,000 moving components. Also most battery electric buses have regenerative braking, and that reduces the brake system to be used around five times less than a conventional diesel vehicle. But you're still going to have the usual maintenance for brakes, suspension, and tires, all that is still required. Although we have seen some reports where they have a reduced need for the number of technicians required to maintain the trucks. So this means a smaller technician to truck ratio, and therefore potentially reduced labor costs of technicians.
Technicians have also reported additional benefits of the trucks just being a little easier to work on because the components are easier to access. You also have a need of fewer components to access for maintenance. This results in quicker repairs. They've also noted cleaner working environments and just a little more pleasant air quality as well with an EV compared to some diesel baseline systems.
But however keep in mind right now since battery electric school buses is an emerging technology that there will be a learning curve to train the technicians on this new technology. And this learning curve may also require some additional training, as well as equipment costs in order to properly have the right maintenance in place for the electric vehicle.
So the techs need to know the difference between the product architecture, so the EV versus the internal combustion engine. Also need to develop an understanding of basic electrical systems, and this is not just DC. It could be AC and at least three-phase, because these are usually high voltage systems. It also may require some updating of tools and personal protective equipment. A lot of that again is related to the high voltage systems, and right now some of the training is still really being developed and standardized. So it's maybe a little difficult to access or find kind of common training at the time. It is under development though, and a lot of OEMs offer this technician training with their products.
Let's see, something else to keep in mind is that tires have experienced an accelerated wear rate compared to the diesel equivalent due to the torque transfer and increased braking force from that regenerative braking system. Industry members have recognized the need for new tire technologies to increase load carrying capacity and reduce rolling resistance in order to improve the overall wear. So something they're working on, but something to keep in mind.
Let's see, in addition to these expected reduced maintenance costs and some of the labor costs we recommend conducting a maintenance analysis to track down the high-cost parts in order to reduce your total cost of ownership. So this is something that is particularly helpful when you are transitioning to a newer technology. I'm going to present a quick example of how the National Renewable Energy Laboratory conducted maintenance analysis on a transit electric fleet.
So we collect all work orders for the evaluation buses, and we calculate a maintenance cost per mile. The cost for accident-related repairs, which are extremely variable from bus to bus, are eliminated from the analysis. The warranty costs are covered in the capital cost of the bus, so those are also excluded. And then for a consistency we just defined a $50 per hour labor rate. So in order to calculate this cost per mile we take that labor rate, which again we said about $50 per hour, multiply that by the number of hours required, add in the cost of the parts, and then we divide that by the total mileage of that bus.
In addition to this maintenance cost per mile calculation we also categorized the maintenance cost by system to provide insight into what systems have the most cost for each technology. So again, this is just your recommendation, and this information is useful in understanding which costs are driving your total cost of ownership and understanding the benefits or areas of opportunity when transitioning to a different technology.
So I'm going to go through the data just real quick on this. This right here is the monthly scheduled maintenance, which is the lighter bars or that tend to be on bottom. And then unscheduled maintenance, darker bars on top, for a battery electric bus transit fleet. The scheduled maintenance is low cost, pretty consistent, doesn't change much. And this is also expected for battery electric school bus. Anything that requires a safety component check similar to a diesel system.
The unscheduled checks though are the top bars and the darker bars, and they're low in the beginning when buses are in warranty, but then you can see that they start to increase, and that increase is what we want to understand if it's just a parts or the labor required for that, or where the issue may be.
So this is the same data, but in this case we illustrate the parts verse the labor costs again to identify what's driving that higher cost. So the light bars are cost per mile. Those are on the bottom, and the dark bars are the labor costs per mile. So the cost of the parts, as you can see here, were greater than the cost of labor. And again, especially after that warranty period is up. So warranty period ends, parts start to fail due to aging or maybe just early design, and you can see that's what's driving up some of your maintenance costs.
This did come from an earlier model battery electric bus. I believe this report was conducted or this analysis was conducted in 2014. So there have been a lot of technology improvements, but again it's helpful in tracking your maintenance parts and maintenance labor cost just to understand what's driving some of those and identify areas of opportunity. Maybe you need to follow up with the OEM or understand why that part keeps failing. Or maybe you need to invest in more training of labor because it's taking a really long time, or you just have to continue to revisit the same issue.
So just want to recap on all of our maintenance costs. Battery electric school buses tend to experience less maintenance requirements and therefore are expected to reduce maintenance cost, as well as labor costs as compared to diesel baseline systems. But do expect a learning curve for technicians and remember that trainings are still being developed and standardized for these technologies. You may experience some additional upfront costs for maintenance, which would likely require updating that personal protective equipment and tools in order to meet the requirements for some of these high voltage systems.
We've also had reports of tires experiencing accelerated wear as compared to diesel systems, and therefore we recommend tracking maintenance costs to identify areas of opportunities and this can be more easily done by calculating the cost per mile and just understanding maintenance cost per system or the labor requirements may help reduce that total cost of ownership because you can identify which area is driving up your cost.
So thanks for listening. That concludes Module 3 Electric School Bus Cost Factors. To complete the modules of this series please continue on to listen to Modules 4 and 5.
And remember, you can find all the content for Flipping the Switch on Electric School Buses series, including each of the series associated modules as well as the handouts with a summary of information and links to all the resources mentioned today on the Alternative Fuels Data Center's Electric School Bus Page.